Polyfunctional alkoxy endblocked polysiloxanes and their cured compositions



not is a linear polysiloxane.

upon" exposure to moisture.

3 161,614 POLYFUNCTIONAL ALKOXY ENDBLOCKED POLYSILOXANES AND THEE CURED COM- POSITIONS Paul L. Brown, Saginaw, and James Franklin Hyde, Midland, Mich, assignors to Dow Corning Corporation, Midland, Mich, a corporation of Michigan No Drawing. Filed Oct. 16, 1961, Ser. No. 145,455 6 Claims. (Cl. 250-465) This invention relates to polysiloxanes in which the terminal silicon atoms each have at least two alkoxy groups attached thereto.

Organopolysiloxanes in which the terminal silicon atoms have one alkoxy group attached thereto are known in the art. However, when these materials are hydrolyzed and the hydrolyzate condensed, the resulting prod- Therefore, these siloxanes are not curable to form thermoset resins or rubbers.

It is the primary object of this invention to provide polyfunctional organosilicon compounds of known structure' which are capable of being cured at room temperature to produce siloxane rubbery materials. It has been United States Patent known for some time that one could mix hydroxylated polysiloxanes with alkoxysilanes in the presence of certain catalysts to produce a composition which will cure at room temperature, 7 However, all heretofore known compositions ofthis type belong to the so-called two component roomtemperature curing siloxane rubbers. In other words, with the previously prepared siloxane compositions the mixing of the siloxane, the alkoxysilane and a catalyst cause spontaneous curing. Although these materials are highly useful in many applications, there are other applications in which it ishighly desirable not to have to premix several ingredients on the job site. Also with the heretofore known room temperature curing compositions once the catalyst, polysiloxane and alkoxysilane were mixed, the composition had to be used within a few hours or else it would gel and become useless. For many commercial applications, this restriction was no hindrance to the use of the materials. However, it left the user open to serious loss of material if anythin'g happened between the time of mixing and the time. of use so that he was unable to employ the material in which case the unused portion of the batch would gel and become usep less.

Conse'quently,it is a primary object of this invention to provide a novel composition of matter which is capable of being mixed with a catalyst in the absence of moisture and which will under these conditions remain stable indefinitely but which will cure spontaneously Another objectris to pro: ducecompositions of matter which are useful as coating compositions, sealants, calking materials, electrical insulation, and for other uses for which siloxane rubbers are normally employed. 1

, The term moisture as used herein includes both water and water vapor including atmospheric water vapor. a V v d This invention relates to siloxanes in whichth'e molecules are essentiallyof the formula 3,lhl,bl4 Patented Dec. 15, 1964 in which R is an aliphatic hydrocarbon radical or halogenated aliphatic hydrocarbon radical of from 1 to 8 inclusive carbon atoms, R and R" are each selected from the group consisting of monovalent hydrocarbon radicals, monovalent halohydrocarbon radicals and monovalent cyanoalkyl radicals, all of from 1 to 18 inclusive carbon atoms, n has an average value from 2 to 3 inclusive, y has an average value from 1.99 to 2 inclusive, 2 has an average value from 1 to 1.01 and the sum of y and z is 3 and x has a value of at least 7.

It can be seen from the formula that the compositions can be both linear and branched in structure. However, the molecules are characterized by having two or three alkoxy groups attached to the terminal silicon atoms.

The term molecules essentially of the formula means that the siloxanes in general have the configuration shown above, but that the compositions within the scope of this invention can also contain some alkoxy and/ or haloalkoxy groups dispersed along the molecular chain due' to incidental hydrolysis and condensation of the terminal alkoxies. Thus, for example, some of the molecular species can have the configuration The compositions ofthis invention can be prepared by several methods. The best method is to react an hydroxylated siloxane of the formula I with a chlorosilane of the formula R' (RO) SiCl in the presence of a hydrogen halide acceptor such as pyridine, alpha-picoline or other tertiary amines. Under these conditions reaction occurs at room temperature between the chlorine on the silane and the hydroxyl groups on the siloxane to produce HCl and to cause linking of the silane with the siloxane through an SiOSi linkage.

The above hydroxylated siloxanes can be prepared by any of the methods commonly employed to prepare such materials such as that shown in US. Patent No. 2,779,776. A second method of preparing the compositions of this invention is to react a halogenendblocked siloxane of the formula with an alcohol of the formula ROI-I in the presence of a hydrogen halide acceptor such as those described above.

I This reaction proceeds at room temperature and the number of OR groups on the silicon will correspond to'the number of chlorine atoms in the original siloxane.

- Another method of preparing those compositions where R is haloalkyl is that of reacting the above halogen endblocked siloxanes with alkylene oxides such as ethylene oxide, 1,2-propylene oxide and 11,2-butylene oxide. This 3 reaction goes at room temperature according to the schematic equation B can be either H or an alkoxy radical.

Another method of preparing the compositions of this invention comprises reacting in the absence of moisture the above hydroxylated siloxanes with silanes of the formula R Si(OR) when a is 3 or 4 in the presence of a catalyst for the reaction of a SiOH with a silicon-bonded OR group. Suitable catalysts include amines and carboxylic acid salts of metals such as lead, tin and iron. This reaction can be represented as follows:

RIFn

(a o) Siol I. ROH

S x Si(OR)n In carrying out this reaction more than one 15101 of the silane should be used per moi of SiOH in the siloxaiie. This will minimize the reaction of an one silane molecule with two hydroxyl groups. The reaction proceeds at room temperature but higher temperatures may be eniployed if desired. If desired the ray-produced alcohol can be removed fro'iritlie product but this is not essential.

If desired, the compositions of this invention can be mixed with fillers such' as those commonly employed in organosilicon rubbers and with a curing catalyst thereafter expose to moisture and allowed to cure. The fillers which can be employed herein are organic fillers such as phthalocyanine and copper phthalo'cyanine and inorganic fillers such as carbon black, glass, aluminum silicate, silicas such as diatoinaceous earth, ground quartz, fume silica, silica xerogel and precipitated silicas and metal oxides such as alumina, titan'ia, Zirconia, zinc oxide, ferric oxide and magnesium oxide. The amount of filler is not critical and depends entirely upon the particular use to which the composition is to be put.

The compositions of this invention are stable in the absence of moisture whether catalyzed or not. The catalyst employed to cure the compositions of this invention can be any catalyst capable of causing the reaction of an alkoxysiloxane with water and of causing reaction between an SiOH group and a silicon-bonded alkoxy group. If desired, mutual solvents may be used to increase the solubility of the catalyst in the siloxane. One class of catalyst includes metal salts of m'on'o'carboxyli'c acids such as lead 2-ethyl octoate, dibutyl tin diacetate', dibutyl tin di-Z-ethyl hexoate, dibutyl tin dilaurate, butyl tin tri-2- ethyl hexoate, iron 2-ethyl hexoate, cobalt Z-ethyl h'exoate, manganese 2-e'thylhexoate, zinc 2-ethyl hexoate, stannous cctoate, tin naphthenate, zirconium octoate, antimony octoate, bismuth naphthenate, tin oleate, tin butyrate, zinc naphthenate, zinc stea'rate and titanium naphthenate. The stan'nous carboxylates and certain orthotitanates and partial condensates thereof are preferred.

Another class of catalyst are titanium esters such as tetrabutyltitanate, tetra-2-ethylhexyltitanate, tetr-aphenyltitanate, tetraoctadecylti'tanate, triethanolaminetitanate, octyleneglycotitanate and bis-acetylacetonyldiisopropyltitanate.

Additional suitable catalysts include amines such as hexyl'amine, dod'ecylamine, and amine salts such as hexylamineacetate, dodeeylaminephosphate and quaternary amine salts such as benzyltrimethylammoniuma'cetate and salts of alkali metals such as potassium acetate.

For the purpose of this invention the amount of catalyst is not critical but is normally present irraniount 01f from .-1 m2 percent based on the weight of the siloxane. The siloxanes employed in'this' invention can range from low viscosity fluids in which x has a value of 7 up to nontlowing gums in which x has a value of 5,000 or more. When maximum stress strain properties are desired, x should have a value of or more. However, when fluid coating compositions are desired, it is often desirable that x have a value from 7 to 100. If x is below 7, the condensates form a high amount of cyclic material and is hence undesirable for curing compositions.

For the purpose of this invention, R can be any aliphatic radical of from 1 to 8, preferably 1 to 3 inclusive carbon atoms such as methyl, ethyl, propyl, isopropyl, allyl, butyl, 2-ethylbutyl and octyl. v R can also be any haloaliphatic radical of 1 to- 8 carbon atoms in which there is no halogen alpha to the silicon-bonded oxygen. Specific examples of such radicals are B-chloroethyl, fi-bromopropyl 2,2,2-trifluoroethyl, 3,3,3,2,2-pentafiuoropropyl, (CH C F gamma-iodopropyl, S-chlorooctyl, ,H-chloroisoprop'yl, omega-chlorooctyl and 3-chloro-2- ethylhexyl.

R and R" cau be any monovalent hydrocarbon radical such as alkyl radicals such as methyl, ethyl; isopropyl, hexyl or octadecyl; any alkenyl radical such as vinyl, hexenyl; any cycloaliphatic radical such as cyclohexyl, cyclopentyl, cyclohexenyl; any alkaryl radical such as benzyl, fi-phenyle'thyl, liphenylpropyl and any aromatic hydrocarbon radical such as phenyl, xenyl; tolyl, naphth-yl, or xylyl.

Both R and R" can also be any halogenated monovalent hydrocarbon radical such as gamma-chloropiopyl, perfluorovinyl, 3,3,3-trifluoropropyl, chlorophenyl," tetrabror'nophenyl, chloroxcnyl, chlorocyclohexyl and u, a,u-triftuorotolyl. In addition R and R" can both be any cyanoa'lkyl radical such as payers-ethyl, gamma cyan o propyl, omega-'cyar'r'obutyl, aeyaaebutyl and omegacy-an'ooct'adecyl.

It should be understood that the various R and R" groups in any one molecule can be the same or they can be different. Thus, the compositions can be hoiiiopolymers or ee ei me'rs. Furthermorefilie concessions can be mixtures of different liomopolyrr'iers and copolymers or mixtures of copolymers and homdfiolyniers; Arse any composition the R groups can be the sensor different.

The following examples are illustfative only should not be construed as limiting the invention which is properly delineated in the appended claims.

EXAMPLE 1 A mixture of 200 g. of an hydroxyl end blocked dime'thylpolysiloxane having a viscosity of 2,000 es, 200 ml. of toluene and 10g. of pyridine was added to a solution of 3.1 g. of silicon tetrachloride in 100 m1. of toluene Reaction occurred to give a silox'ane having the average formula l onsio[s iolwsion After mixing for approximately 30 minutes, 6 g. of methanol was added and the reaction mixture agitated for another 30 minutes.

The pyridine hydrochloride was filtered and the solvent was removed under reduced pressure to a pot temperature of about C. The stripped product corresponded to the average formula Me; (MeO) SiO (S iO mSKOMe);

This material was stable in the absence of moistureeven when catalyzed with di-n-hexylamine. However, when a mixture of the material and di-n-hexylamine wereexposed to atmospheric moisture, it cured to a rubberymaterial.

EXAMPLE 2 1 g. of methyltrichlorosilane was added rapidly to a mixture of 100 g. of anhydroxyl enblocked dimethylepolysiloxane having a viscosity of 13,000 cs., 200'ml. of.

r w r (Me),sio s10 msiwMe), The product Wasmixed with di-n-hexylamine and was stable in the absence of moisture but curedto a rubbery material upon exposure to atmospheric moisture.

a viscosity of 12,150 cs. and having the average molecular.

formula Alie 7 I (ntonsio s10 nSi(OEt) This material was stable in the absence of moisture but gelled when mixed with di-n-hexylamine and thereafter exposed to the atmosphere. 1

EXAMPLE 4 The following siloxanes are obtained when the following hydroxylated siloxanes are reacted with the following alkoxychlorosilanes in accordance with the procedure of Example 3.

g. of triethoitychlorosilane was added to a jrniprture of 500 g. of an hy droxyl enblocked dimethylpolys'iloiianeof 13,000 cs. viscosity, 1,000 ml. oftoluene ahd lOQfl-il.

v of'pyridine. After mixing .for .3Q i 1 F Q 0 .0

ethanol was .added to reactv with any iemaining chlorinebonded'siliconfIAfter allowing another 30 minutes for Table I Hydroxylated Siloxane Ohloroalkoxysilane Product Me -C2Ha Me Q2113 HO[S iO ]H Czfia MeO)zSiCl (MeO )1Si(!) [do :ino e 321 5 100 l '4 (11115 no Phn Me; C6H3C12 P112 Me: CsHaClz no: siio)i(sio)w H ClflQuHKMBOMSlCl (Me0)zSi( [(sio)r(sio)ta]s'i oMe)r Me .1 I ,e g (OMe)z Me (0M0): new )3 oHmoHoms oMe ci onmonoms io [he siomom onm 710 31 I 18112.1 20 Men i 01 creamer. Meg 011,011,013 noiisiol n V CFzCHaCHiS KOMQM M onslo [$015.0 suoMe omomom Me omomom Me 11o\:sio 1H a esuoMe o Meo isio\:sio KOMe): li/[e' 20 I will 7 il /1e an anionic .7 'Ph oniomon Ph Ho sio 5 I rhsuoMa oi Meohs ioFio sl OMe h 1e loo V 1319 mu 7 Ph r Ph 7 V H0(dio)11 (rainwater; oan1o)asio[siio] srwomm 1\ Ie 20 V i I i I Il /1e to,

y i Y Cu 11 Mel on Me, i CaHu M62 osimMe Mei 0611 {(0% )MOi (bit-X0101; o'an su oMenor (MeOhSiO (io iorii-o- SiO so ditoMen a Ii/1e v Mez I v c2115 7 C2115 Meg C2115 nouiolwn (omOnA-bnomolsror (omombnonzolsio[sio]msi(oomhnomom) Me Me; Me Me; 1 M8 S i osi-o-i OH I Mesigoivrmor Si OSi- -(i-Si 0S i(0Me)i Me 100 s r Me 106 a 1 Meg V 1 Me: Me

i.si[ osi )1coOH]4 I esigoMsjioi. f Si[ O i umOS i(OMe )2]4 EXAMPLE: 3 Each of the abovecompounds is stable when mixe with .5 percent by weight dibutyl tin dilaurate and store in the absence of moisture, but will cure at room ten perature when-the mixture isexposed to moisture.

a 10 ml. of silicontetrachloride was added to an anh r g v v drous mixtureof 250 m1. of Xylene, 100 of toluer the reaction to'be complete, the solids. were removed V A I I and ml. of a-picoline. 250 g. of a 1,140 cs. hydrox and thesolvent was strippedofi togive ayroducthaving 7 5 endblocked dimethylpolysiloxane was thenadded'wit stirring. After so minutes the excess s'ilicontetrachloi-ide' This material was mixed with n-hexylamine and the mixture was stable in the absence of moisture but cured oh exposure to atmosphere to a rubbery gel.

EXAMPLE 6 The procedure of Example was repeated except that 30 ml. of delta-chlorobutanol was employed. The resiflting siloxane had a viscosity of about 2,000 es. aid an average formula This material was mixed with n-hexylamine and it was stable in the absence of moisture but cured to a rubbery solid on exposure to the atmosphere.

EXAMPLE 7 ml. of silicontetr'achloiide was added to an anhydrous solution of 250 ml. of xylene, 100 ml. toluene and 30 ml. of a-picoline. 250 g. of 1140 cs. hydroxyl endblocked dimethylpolysiloxane was then added with stirring. The mixture was cooled to about 0 'C. and 100 ml. of liquid ethylene oxide was added. The mixture was allowed to warm to room temperature and was stirred over-night. The solution was filtered and the solvent was removed. The product was redissolved in dry toluene and the solution was filtered and the toluene removed. The resulting siloxane had a viscosity of abodt 1 140 cs. and had the formula This material was stable when mixed with hexylamine in the absence of moisture but the mixture c'ufe'd in' 2 minutes on exposure to moisture to give a rubbery material.

EXAMPLE 8 The pro'edure of Example 7 was repeated except that 100 ml. of 1,2-p'ropanol oxide was employed. The resulting siloxane was a viscous fluid in which the structure was essentially that of a diniethylpolysiloxane having terminal groups in which the terminal silicon atoms had 3-gamm a-chloropropoxy groups attached thereto.

EXAMPLE 9 300 g. of a 2000 cs. hydroxyl endblocked dimthylpolysiloxane was dissolved in 300 g. of toluene and 10 g. of pyridine. 4.5 g. of the methyltrichlorosilane was then added with stirring and after 30 minutes B-cliloropropanol was added with stirring. After 30 minutes the pyridine hydrochloride was filtered and thesolvents and volatile materials were removed by distillation. The resulting liquid product was a siloxane having the average formula This. material was stable in the absence of moisture when mixed with hexylamine but the mixture gelled to a rubbery material when exposed to atmospheric moisture: r

.. EXAMPLE 10 I 366g. of a 20tl'0 cs. hydroxyl endblocked dimetliyL olysiloxane was dissolved in 300 g. of toluene and 10 g.

of py'r'icline- The mixture was stirred and 4.5 g. of methyltriehlor'osilane' was added; After 30 minutes 9 g. of 3,-3,3-'trifluorothanolwas added. After 30 minutes stirring the pyridine-hydrochloride was filtered and the solvent and ether vsia'fiies removed by distillation. The resulting fluid siloxane had the average formula 1 148 'lti le (C F3CHgO)gSlO[SlO]Sl(O CHgC Fzh This material was stable when mixed with hexylamine in the absence of moisture but cured in a short while when exposed to moisture to a rubbery material.

EXAMPLE 11 5 g. of a 5000 cs. hydroxyl endblocked dimethylpolysiloxane was mixed with 3 g. of tetrakis-3,3,3-trifluoro-ethoxysilane and l g. of propanol. The latter was added to increase the compatibility of the system. .07 g. of di-n-hexylamine was then added, the mixture became clear showing reaction between the siloxane and silane to produce a fluid siloxane of the average formula Me 0 n,on,o ,sio[sid]si oomo Fa):

in which R is selected from the group consisting of monovalent haloaliphatic hydrocarbon radicals having no halogen on the carbon alpha to the oxygen and monovalent aliphatic hydrocarbons radicals both of said radicals havings from 1 to 8 inclusive carbon atoms, both R and R" are each selected from the group consisting of monovalent hydrocarbon radicals, monovalent halohydrocarbon radicals and monovalent cyanoalkyl radicals all of from 1 to 18 carbon atoms, n has an average value from 2 to 3 inclusive, y has an average value from 1.99 to 2 inclusive, z has an average value from 1 to 1.01 inclusive and the sum of y+z is 3 and x has a value of at least 7.

2. A composition in accordance with claim 1 where R, R' and R are all methyl radicals.

3. A curable composition of matter which is stable in the absence of moisture but which will cure upon exposure to atmospheric moisture consisting essentially of (l) a siloxane in which the molecules are essentially of the formula llla-n I y lli's-ii (R0).si0 si0 snort).

'R each are selected from the group consisting of monovalent hydrocarbon radicals, monovalent halohydrocarbon radicals and monovalent cyanoalkyl radicals, all of from 1 to 18 inclusive carbon atoms, n has an average value from 2 w 3 inclusive, 'y has an average value from 1.99 to 2iii'clu'siv'e', 2 has an avera e value from 1 to 1.01

inelusive and the sum of y+z is 3 max has a value of at least 7 and (2) a curing catalyst for the siloxane.

4. A ;composi tion in accordance with claim 3 which "518 includes a fine-r.

5. A composition in accordance with claim 3 in which R, R and'R" are all methyl radicals.

6; The method of forming a cured material which comprises exposing the composition of claim 3 to moisture.

3/54 8/55 10/55 4/56 z/s s References Cited by the Examiner UNITED STATES PATENTS Dexter 260-465 1 0 2,815,300 12/57 Smith 260-465 2,909,549 10/ 59 Bailey 260-4482 3,035,016 5/62 Brunet 26046.5 3,109,826 11/63 Smith 7 26037 OTHER REFERENCES Paint, Oil and Chemical Review, March 22,1956, pp. 10-12.

MURRAY TILLMAN, Primary Examiner. I. R. LIBERMAN, WILLIAM H. SHORT, Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,161, 614 December 1 5, 1964 Paul L. Brown et al.

It is hereby certified that'error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Columns 5 and 6, Table I, third column, the second formula should appear as shown below instead of as in the patent:

C H3Cl Phz M 2 6 3Cl2 (MeO) Si O SiO SiO 9 Si(OMe) column 8, lines 30 to 34, the formula should appear as shown below instead of as in thepatent:

R R y R (RO) SiO SiO Si(OR) Z Signed and sealed this 13th day of July 1965.

(S Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A SILOXANE OF THE FORMULA 